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47 Cards in this Set
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The Cell Theory |
M. Schledian & T. Schwann, Rudolf Virchow |
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What is the cell theory? |
1. All organisms are composed of one or more cells 2. Cells are the smallest living units of all living organisms 3. Cells arise only by division of a previously existing cell 4. Cells vary in size and shapes |
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2 types of cells known in biology |
Prokaryotic and Eukaryotic Cells |
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Prokaryotic cells |
Before the appearance of nucleus. No nucleus. Unicellular |
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Eukaryotic Cells |
True and distinct nucleus. Uni/Multicellular |
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Elastic, double layers of protein and fatty materials which form special surfaces over almost all subcellular organelles as well as over entire cells |
Plasmalemma - the cell membrane |
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What is the major function of the plasmalemma? |
Regulates the critical exchange of materials between the cell and it's environment, maintaining a protected and yet open system in which nutrients are selectively brought in and waste products and secretions selectively removed |
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What is the hydrophilic portion of a plasmalemma? |
Basic phospholipid group and phosphate group of phospholipids |
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What is the hydrophobic portion of a plasmalemma? |
Chain of fatty acids and cholesterol |
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Cell membranes are composed of...? |
Lipids (especially phospholipids), proteins and carbohydrate coating |
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Membrane lipids have....? |
Hydrophilic heads and hydrophobic tails, and when surrounded by water they assemble spontaneously into a bilayer. All heads are at the two outer faces of a lipid bilayer and all tails are sandwiched between them |
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Fluidity of the membrane |
1. Lateral Diffusion - 10^7 times per second 2. Flip Flop - rare once a month 3. Flexion 4. Rotation |
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Bonds on the hydrophobic tails of the lipid bilayer? |
Cis double bonds |
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Cell membrane functions |
1. Transport 2. Enzymatic activity 3. Signal Transduction 4. Cell-cell recognition 5. Intercellular joining 6. Attachment to the cytoskeleton and extracellular matrix (ECM) |
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Synthesis of a membrane? |
Old membrane provides a template for new membranes |
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What is the living environment of cells? |
The Extracellular matrix |
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Region of intensive ribosomal RNA synthesis |
Nucleolus |
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May be described as a minute channel conveying proteins through the canals onto the Golgi complex |
Endoplasmic Reticulum |
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Involved in the protein synthesis and best seen in cells active in protein secretion like the pancreatic exocrine cells and liver cells |
Rough ER (With ribosomes) |
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Also have membranous canals but ribosomes are lacking, site of lipid synthesis (e.g steroid hormones of adrenal glands) |
Smooth ER |
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Consists of several flattened tubular membranes piled upon each other called Golgi bodies |
Golgi complex (Dictyosomes) |
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Have powerful digestive capability. Contain enzymes collectively known as acid hydrolases which are capable of breaking intracellular biomolecules as well as digesting foreign organisms entering the cell |
Lysosomes |
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Ovoid structures limited which isolate a group of enzymes used in a metabolic pathways from the rest of the cellular chemistry. Contains catalses, peroxidase, and other oxidases. Concerned also with purine metabolism or breakdown of nucleic acids and conversion of fats to glucose |
Peroxisomes |
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Very small particles composed of RNA and protein, can be free or bound to ER or linked together into long chains of polysomes, site if protein synthesis, assembled in nucleoli |
Ribosomes |
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Rod like structures within the centrosome, made of protein. Active in the process of cell division |
Centrioles |
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Organelles containing centrioles, involved in the process of cell division |
Centrosome |
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A mesh of filamentous elements (microtubules, microfilaments, intermediate filaments), provides structural stability for the maintenance of cell shape, cell movement and cell component rearrangement |
Cytoskeleton |
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A model if cytoplasmic organization wherein all organelles and inclusions are embedded in a delicate meshwork |
Microtrabecular lattice |
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Both ... And.... Serve to move the cell through the environment or move fluid (of the environment) past the surface of the cell. Both have 9+2 arrangement of microtubules |
Cilia and flagella |
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Organelle formed from a centriole. Found at the base if a eukaryotic cell cilium or flagellum and serves as a nucleation site for the growth of the axoneme microtubules. --- anchor cilia |
Basal body |
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Microfilaments are usually composed of?? |
Actin protein |
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Membranous sacs, contains ingested materials or cellular secretions or waste |
Vacuoles |
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Possess a double layered membrane wherein the inner layer membrane is extensively infolded producing shelves called cristae |
Mitochondria (Chondriosomes) |
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What is the function of the mitochondria? |
Involved in cellular respiration or the process of ATP production to support mechanical and chemical works performed by the cells |
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Cell membrane functions: Membrane Transport Systems Non-mediated processes (without the aid of transport proteins) |
1. Bulk flow2. Diffusion3. Osmosis4. Dialysis |
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Cell membrane functions: Membrane Transport Systems mediated processes (with the aid of transport proteins) |
1. Facilitated diffusion 2. Active transport |
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What is the driving force of diffusion? |
Concentration gradient. From a region of high concentration to a region of low concentration until the molecules are evenly distributed |
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Factors affecting the rate of diffusion |
1. Concentration gradient 2. Cross sectional area through which diffusion occurs 3. Temperature 4. Molecular weight of the diffusing substance 5. The distance through which diffusion occurs 6. Presence of other molecules |
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Osmosis |
Diffusion of a solvent (usu. water) Higher conc of water (dilute solution) to a region of lower conc of water (conc solution) Only water molecules equilibriate |
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Hypertonic solution |
Low water conc so conc sol. Water will move out of the cell. Shrinking or shriveling |
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Hypotonic solution |
High water conc so low solute conc Water will move into the cell - rupture of the membrane |
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Plasmolysis vs hemolysis |
P for plants Hemo for RBCs |
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Diffusion of a dissolved substance through a semi permeable membrane |
Dialysis |
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Passive vs active |
Passive - no cellular energy Active - needs energy |
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Cytoplasmic vesicles containing macromolecules travel to the plasma membrane where the vesicular and the plasma membrane fuse and the macromolecules are released into the extracellular fluid |
Exocytosis |
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Opposite of exocytosis. |
Endocytosis |
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Cellular eating? Drinking? |
Phagocytosis Pinocytosis |